I assume you are asking about the module by the rearview mirror. Sorry, didn't take pics when I did it. Not sure if the design has changed, but I have a 2001 Suburban LT.
I removed both sun visors and the overhead console. Visors: Once the screws are removed, pull out the visor and there will be a wire harness you can disconnet to completely remove the visor from the headliner. The overhead console has one screw towards the front and one clip at each corner towards the back. Remove the screw then pull the back part of the console down with your hands. Disconnect the wire harness to completely remove it from the headliner. At this point you can remove the small black Onstar microphone clipped to the side of the overhead console. Now the headliner can come down enough so you have room to work.
My Onstar bracket was secured by one rivet. You can drill it out and remove the bracket. I was lazy and didn't want metal shavings everywhere, so I just got a big pry bar and removed it that way. That's it.
The antennas and dash buttons are simple. When removing the dash buttons, just be ready with what you want to put there in its place (storage pocket, bottle opener, bass knob, lcd monitor, etc).